It is accepted that the spirit level (niveau à bulle d'air) was invented by Melchisedech Thevenot (1620 - 1692) some time before February 2, 1661. However, some people interpret a 1558 text, referring to an insect, as mentioning a spirit level more than one hundred years before it was created by Thevenot...

A 1558 French text describing a spirit level more than 100 years before it was invented?!

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Histoire entière des poissons, Guillaume Rondelet, 1558

enter image description here Plumb bob level [fil à plomb, plomb, niveau à]

Do you, as a native French speaker, consider that the text talks about a spirit level or does the paragraph refer to a plumb bob level, a tool invented in antiquity?

  • 1
    It says the insect has the shape of a T or a level ("niveau"), with three feet on each side (or three feet overall). Does not look like a Spirit Level ("Niveau à bulle" in french). There is no mention of a bubble ("bulle") anywhere. Feb 2, 2016 at 11:04
  • Parce que je ne suis pas sûr que ce soit la réponse, ça se discute justement. Feb 2, 2016 at 14:35

1 Answer 1


The text describes the freshwater insect that is called by the author "niveau d'eau douce" and is drawn just below the title. Looking like a hammer shark, its T shape evokes a "niveau". It also has three legs on each side.

In this text, the only reference to an inclinometer is the word "niveau". It is used to give a name to the insect because their shapes are similar.

As indicated by @SimonMourier, there is no indication of the level technology (spirit or plumb bob level).

 The insect is a dragonfly larvae (larve de libellule)

  • It became clear that the 1558 text refers to a T shape level which was called "hammer fish" in Italy, that time. This is a plumb bob level. A spirit level is not like a T and has no common features with the insect described in the book. Feb 3, 2016 at 8:51

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